On the outside, school buses haven't changed much in almost 100 years, and there's a reason for that. A 1939 conference determined the yellow color, black text, and boxy shape that have come to symbolize the iconic childhood transport. Buses have changed a lot on the inside since the conference and they continue to be the safest way to get to school — about 70 times safer than a car, according to the US National Highway Traffic Safety Administration.